This patent generally relates to analog-to-digital conversion and, more particularly, to a calibration scheme used for one or more of the stages in pipeline Analog-to-Digital converters (ADCs).
Pipeline ADCs are a preferred architecture for medium to high speed, high resolution ADCs. Pipeline ADCs have lower power consumption and lower comparator accuracy than flash ADCs and higher throughput due to the pipelining of lower accuracy stages compared to cyclic ADCs. Pipeline ADCs are switched capacitor circuits relying on capacitor matching and high op-amp open loop gain to achieve high accuracy. In applications where distortion has to be very low, the need for accuracy is high, and calibration of capacitor mismatches and finite op-amp open loop gain is essential.